AdvertisementInvestigators Say 'Explosive Device' Caused St. Petersburg Metro Train BlastApril 03, 2017Merrit KennedyBill ChappellfacebookEmailA damaged train carriage sits at the Technological Institute metro station in St. Petersburg, Russia. At least 10 people were killed and dozens more were injured Monday afternoon after an explosion went off in between metro stations in Russia's second-largest city. (AFP/Getty Images)